The present invention relates to a release-controlled pipe and a related manufacturing method, especially to a manufacturing process which improves the quality of a release-controlled pipe. The manufacturing process includes the following steps: formulation blending, first hot melt extrusion, stirring and shattering, second hot melt extrusion, and cooling. When the second hot melt extrusion is performed with ground pellets and water, the water serving as a vesicant, a uniform release-controlled pipe with good dispersion can be manufactured. Also, the cost of manufacturing and production can be reduced. In this way, the present invention constitutes a practical advancement which will be beneficial to the industry.
Release-controlled pipes have many applications, especially in agriculture. Manufacturing of a release-controlled pipe is not an easy matter, such as shown in U.S. Pat. No. 4,517,316 and in FIG. 1 herein. The referenced patent relates to a common manufacturing process for a release-controlled pipe, which mainly includes the following steps. First, the formulation is blended and shattered, then it is extruded via a compounding extruder. After water cooling is performed, pellets of the compounds are dried on a conveyor and then bagged. Then the pellets of the compounds are poured into a second extruder. After being heated to the molten temperature via three successive heating devices, the pellets are extruded to form release-controlled pipes, then cooled and gathered.
Using the release-controlled pipe produced from the foregoing manufacturing process may result in the following disadvantages:
1. The commonly used manufacturing process includes many steps, and requires many mechanical devices, so the cost is high.
2. The amount of dispersion of release-controlled pipes depends upon the number of gas holes. Therefore, for a release-controlled pipe to have good dispersion, except for the formulation, the water content during formulation and extrusion molding is important. However, the amount of water content in the formulation of the commonly used manufacturing process is not easily controlled, resulting in a low quality release-controlled pipe.
The first purpose of the present invention is to provide a simpler, less expensive manufacturing process of a release-controlled pipe.
The second purpose of the present invention is to provide a release-controlled pipe with better dispersion, which has better soaking and dispersing effects.
The third purpose of the present invention is to provide a new method for industry use that can be free of unessential components or mechanical devices in the manufacturing process, and can also improve the quality of a release-controlled pipe.
A related manufacturing method for a release-controlled pipe which can achieve the purposes described above comprises the following steps: mixing a formula, first compounding extrusion, cooling, grinding into pieces, blending, secondary extrusion molding and cooling, then gathering the pipe. The dry, ground pellets obtained immediately after the first compounding extrusion step, mixed with pellets including water content, using water as a blowing agent, undergo secondary hot melt extrusion. The quality of the release-controlled pipe is improved with the above manufacturing method.